Generally, the field of three-dimensional computer graphics is concerned with generating and displaying three-dimensional objects in a two-dimensional space, such as a display screen. This is accomplished by converting information about three-dimensional objects into a bit map that is displayed. This so-called rendering process is a multi-part process by which a computer turns an application model description of an image into a screen image. The basic idea is that the processing of information in three-dimensional computer graphics occurs in a series of stages in a graphics pipeline, where each stage generates results for a successive stage.
One type of rendering employs rasterization. In general, rasterization is the process of converting an image described in a vector graphics format (shapes) into a raster image (pixels or dots). The resulting output maybe provided to a display or printer, or saved as a bitmap file, for example. A typical rasterization algorithm receives a three-dimensional scene described as polygons, and renders that scene onto a two-dimensional display. Each polygon is represented as a collection of triangles, and the triangles are each represented by three vertices in three-dimensional space. In this sense, a rasterizer receives a stream of triangle vertices, transforms them into corresponding two-dimensional points on a surface, and fills in the transformed two-dimensional triangles as needed.